Alloy steel



?atented Apr. 23, 19.35

UNlTED STATES ALLOY STEEL Joseph V. Emmons, Shaker Heights, Ohio, as-

signor to The Cleveland Twist Drill Company, Cleveland, Ohio, acorporation oi @hio No Drawing. Application December 22, 1934,

Serial No. 758,754

13 Claims.

This invention relates to ferrous alloys and more particularly to alloysteels in which tungsten is employed as a principal alloyingconstituent. More specifically, this invention relates to that type offerrous alloys or alloy steels which is employed in the form of cuttingtools and wearresisting parts and which type is commonly referred to bythose familiar with the art as an alloy tool steel.

As is well known to those familiar with the art, alloy tool steels have,in the past, been made with tungsten as the principal alloyingconstituent and the types commonly known as high speed steels are atpresent the standard commercial tool steels for high duty machining ofmetallic substances.

The tungsten high speed steel most widely used commercially at thepresent time is essentially an alloy of carbon and iron withapproximately 18% tungsten, 4% chromium and 1% vanadium. This standardtype is commonly known as 18-41 high speed steel. In addition, suchsteel contains minor quantities of such alloying elements and impuritiesas manganese, silicon, copper, sulphur, phosphorus, arsenic, tin, etc.Such elements as cobalt, nickel, uranium and tantalum are sometimesadded to secure certain changes in the properties of the steel.

In my previous U. S. Patent No. 1,937,334, is

disclosed the fact that a very satisfactory steel capable of beingsatisfactorily used for the same purposes for which 18-41 high speedsteel has been used may be secured, if to a steel in which molybdenum isthe principal alloying ingredient, minor amounts of tungsten are addedand if the amount of such tungsten is present in adefined proportionalrelationship to the amount of molybdenum present. It has been explainedthat the unexpectedly desirable results secured by the addition of minoramounts of tungsten to a molybdenum steel as taught in my aboveidentified patent is due to a powerful auxiliary effect which such minoramount of tungsten has upon the molybdenum content of the alloy. Thedesirable results secured by the addition of such ,minor amounts oftungsten to a molybdenum steel are greater than any results which wouldbe expected upon the theory of, equivalencyof tungsten and j molybdenumas taught in the prior art.

The present invention relates to the discovery that molybdenum, whenadded to a ferrous alloy composition, in which tungsten is the principalalloying element, and when thus added in amounts which bear a certainproportional relationship to the amount of tungsten present, has apowerful auxiliary efiect upon such steel. Such results are considerablymore pronounced than those usually achieved by the addition ofmolybdenum to high tungsten steels in accordance with the practices inthe prior art.

It is a principal object of this invention, therefore, to provide aferrous alloy composition, or more particularly, a tool steel of thetype in which tungsten is a principal alloying constituent and to whichthere has also been added a minor amount of molybdenum for its powerfulauxiliary effect, thus producing a steel which, when used for purposesof cutting tools, wear-resisting parts and the like, has performancecharacteristics equal to and in certain respects superior to those ofcomparable steels in the prior art.

It is a further object of my invention to provide a high speed toolsteel of the high tungsten type having cutting or wear-resistingproperties superior to the cutting or wear-resisting properties of thestandard 18'.41 tungsten high speed tool steel.

It is also an object of my invention to provide a high speed tool steelof the high tungsten type substantially equal in cutting orwear-resisting qualities to the standard 18-4-'-1 high speed tool steelbut which contains a materially lesser amount of the expensiveingredient tungsten.

It is also an object of myinvention to provide a high speed tool steelof the type in which tungsten is the alloying element having thedominating effect and which steel has a lower specific gravity thancomparable steels of this type known to the prior art.

It is a further object of my invention to provide high speed tool steelswhich may attain a higher degree of secondary hardness after hardeningand tempering than is usual with the standard 18-4-1 type of steel.

It is still another object of my invention to provide steels having highsecondary hardness and also having high values of strength and ofplasticity developed simultaneously by the same heat treatment so thatsaid steels exhibit exceptional toughness.

' Other objects of my invention will appear as .the descriptionproceeds.

To'the accomplishment of the foregoing and related ends, said invention,then consists of the means hereinafter fully described and particularlypointed out in the claims.

The following description sets forth in detail some approvedcombinations of ingredients embodying my invention, such disclosed meansconstituting, however, but a few of the various forms in which theprinciple of the invention may be used.

The present invention relates, as previously indicated, to the discoverythat certain minor amounts of molybdenum, as hereinafter more fullydefined, when added to a ferrous alloy composition of the type in whichtungsten is a principal alloying ingredient, have a powerful auxiliaryalloyingeffect thereon, considerably greater than any effect ofmolybdenum previously observed in such alloy compositions.

More specifically, this invention comprises the discovery that in theclass of alloy tool steels in which tungsten is the dominationg alloyingelement, there is a definite relationship between tungsten andmolybdenum whichgif properly observed, produces unexpectedly favorableresults.

This relationship is made effective by adding to such steels auxiliarymolybdenum in amounts from about 12% to about 28% of the amount oftungsten present. Such additions have been found to greatly andunexpectedly increase the cutting and wearing quality of tools made fromthe steel. 1

The above given range of from about 12% to 28% for the ratio between thetungsten and molybdenum may be conveniently divided into the followingnarrower ranges, viz:-

Molybdenum from above 12% to about 15% of the tungsten present;

Molybdenum from above 15% to about 25% of the tungsten present;

Molybdenum from above 25% to about 28% of the tungsten present.

The previously defined range for the ratio between the two elements maybe further divided in the following manner, viz:--

Molybdenum from about 12% to about 20% of the amount of tungstenpresent; and

'Molybdenum from above 20% to about 28% of the amount of tungstenpresent.

In the ensuing description wherein will be found a disclosure of a largenumber of alloys, in which the above defined proportional relationshipbetween tungsten .and molybdenum is maintained, it will be noted thatthere are certain groups of compositions which may be convenientlyclassified in the above defined manner.

The broad limits of composition within which this invention resides areas follows:

Carbon about 0.15% toabout 1.60% Silicon a trace to about 3.00% Chromiumabout 3.25% to about 6.00% Tungsten about 8.00% to about 20.00%

Vanadium None to about 6.00% Molybdenum about 0.96% to about 5.60%Cobalt None to about 16.00%

the remainder being substantially iron together with such other alloyingelements and impurities as are sometimes found in this type of alloycomposition.

A somewhat narrower range of compositions is as follows:-

Carbon about 0.65

to about 0.90% Silicon about 0.20% to about 2.20% Chromium about 3.37%to about 4.98% Tungsten about 10.32% to about 19.00% Vanadium about0.45% to about 3.09% Molybdenum about 1.24% to about 5.32% Cobalt Noneto about 14.00%

the remainder being substantially iron together with such other alloyingelements and impurities as are sometimes found in this type of alloycomposition.

A still narrower range of compositions is as follows:-

Carbon about 0.65% to about 0.85% Silicon about 0.27% to about 1.00%Chromium about 3.42% to about 4.73% Tungsten about 11.04% to about16.50% Vanadium about 0.68% to about 2.46% Molybdenum about 1.32% toabout 4.62% Cobalt None to about 12.00%

the remainder being substantially iron together with such other alloyingelements and impurities- 1 Mo Example No. C Cr W M Si Va 00 s 0 Ratio wActual Percent Percent Percent Percent Percent Pereent- Percent 3 0. 724. 05 13. 05 13. 6 1. 78 1. 27 0. 72 0. 63 3. 90 11. 68 14.1 1. 65 1. 16l. 01 0. 66 3. 93 12.00 14. 1 1. 69 2. 20 0. 68 0. 76 3. 78 12. 06 14.3 1. 73 0. 38 1. 80 0. 7O 4. 98 11. 96 14. 6 l. 1. 30 0.67 0. 65 3. 7512. 16 14. 7 1. 79 1. 21 1. 54 0. 73 4. 00 11. 04 14. 7 1; 62 1. l9 0.680. 80 3. 37 11. 89 15. 0 1,. 78 l. 06 2. 46 1. 03 3. 66 11. 76 15. 0 1.76 1. 48 3. 62 0. 90 3. 61 12. 11 l6. 1 1. 83 1. 36 3. 09 0. 65 3. 9211. 06 15. 1 1. 67 0. 47 0. 76 0.83 4. 73 15. 61 15. 2 2. 37 0.27 2. 04

0. 69 3. 71 11. 72 15. 4 1. 80 1. 25 None 1 l. 57 3. 42 11. 76 16. 8 l.98 0. 50 5. 56 0.74 4.05 9.86 17.4 1.72 1.43 0.72 0. 77 4. 09 12. 33 17.4 2. 14 1. 31 0.79 0. 76 3. 92 10. 54 18. 7 l. 97 1. 23 0. 83 0. 77 3.75 14. 00 20. 0 2. 80 0. 40 1. 50 0. 78 4. 00 11. 00 22. 7 2. 50 0. 202. 50 0. 70 3. 90 10. 32 24. 1 2. 49 1. 20 0. 07 0. 70 3. 93' 12. 41 25.0 3. 10 1. 32 0. 76 0. 3. 50 16. 50 27. 3 4. 50 0. 50 0. 75 0. 79 4. 008. 50 28. 0 2. 38 0. 20 3. 00

Attention is directed to the. fact that in the foregoing table thevarious compositions are arranged in the order of the proportionalrelationship therein between molybdenum and tungsten.

In the following table I include certain data in regard to the heattreatment and some of the physical properties of certain of the examplesof the specific alloy compositions included-in the previous table:-

preciably, thus reducing the weight of steel required to make a tool orother article of manufacture.

From the foregoing description, it will be apparent that my inventionrelates not to the substitution of molybdenum for tungsten in high speedtool steels as has been suggested in certain instances in the prior art,but instead to the production of a new type of tungsten steel in which aspecific minor amount of molybdenum is Tempering Maximum MaximumPlasticity at Hardness in Best hardem range for secondary torsionalmaximum pacific gravannealed com Ex. no. in range a F maximum hardnessobstrength obstrength in ity in an dition Rock g secondary servedRockserved in degrees of nealed we B Scale hardness F. well scaleinch-pounds 1 twist 1 condit on 2 2270-2340 990-1140 66. 0 476 126 8. 322310-2340 1040-1140 66. 3 457 34 8. 39 100-101 2270-2350 About 1040 8.36 2270-2340 940-10 65. 3 442 50 8. 29 102-104 2290-2340 940-1140 66. l484 102 8. 38 94- 99 227 0-2340 940-1140 65. 2 431 38 8. 36 99-1002270-2340 840-1040 65. 4 449 96 8. 32 99-100 2270-2310 990-1140 66. 5429 29 8. 29 99-100 2290-23 1040-1140 67. 7 454 45 8. 28 97- 992270-2330 1140-1090 66. 4 435 96 8. 21 2270-2330 940-1140 66. 9 446 568. 24 97-100 2310-2340 990-1140 65. 7 429 48 8. 40 97- 98 2310-2340940-1090 66. 6 449 45 8. 57 96-101 2240-2310 940-1040 65. 4 418 47 8. 35101-102 2250-2310 1140-1190 67. 8 452 58 8. 15 99-100 2270-23301040-1140 8. 25 99-101 2240-2310 940-1040 64. 4 429 67 8. 33 99-1002240-2310 1140-1090 64. 5 446 94 8. 25 98 2240-2270 940-1040 62. 4 8. 28100-104 2240-2340 940-1040 66. 2 453 62 8. 39 100-102 1 For adescription of the method of determining these properties refer toProceedings American Society for Testing Materiils vol. 31,

part II (1931), page 47.

Certain maximum values, such as hardness, given in the foregoing table,are those which have been observed; however, it is possible that highervalues may be attainable by diiferent heat treatments.

While the above values, indicating the best hardening and temperingranges, are the results of actual observations, it is recognized thatthey are a matter of opinion only and for specific purposes, desirable.heat treatments might be found outside these values.

It will be observed that the specific gravities of the examples listedinthe above table are materiallyv lower than those of the 18-4-1 type ofhigh speed steel, the specificgravity of which is generally in excess of8.60.

Particular attention is called to Example Nos. 8 and 14. These steelsshowed outstanding cutting quality when used as drills, their drillingperformance definitely exceeding that of the drills made of 18-4--1 highspeed steel with which they were compared.

Particular attention is also called to the high secondary hardnessdeveloped by Example Nos. 3, 6, 9,10, 11, 12, 14, 16, 23. Hardnesses inexcess of Rockwell C 66 are regarded as being above those ordinarilydeveloped in the 18-4-1 type of high speed steel.

Attention is also called to the high tempering range which is recordedfor Example 16. The values of 940 to 1190 indicate a broad range and ahigh order of red hardness.

The abnormally high plasticity values shown by Examples 2, 6, 8, 11 and19 are caused by the peculiarity that the maximum strength of the steelis developed at a tem peIing temperature so low that it falls within therange of high plasticity.

The high silicon contents of many of theabove examples are found toproduce a very sound, thoroughly deoxldized steel. High silicon alsoreduces the specific gravity of the steel quite ap-- used for itspowerful auxiliary eifect in increasing the cutting and wearingqualities of such steel. By the addition of the auxiliary quantities ofmolybdenum in the above defined specific ratio to the amount oftungstenpresent, I have been able to produce a high speed steel of thetungsten type having cutting properties better than those of themolybdenum-free tungsten steels of the prior art and also 'better thancertain other molybdenum-containing tungsten steels of the prior artwhich lie outside the above specified range of ratios of molybdenum totungsten and with which comparisons have been made.

A wide variety of heat treatments may be employed in connection'with theabove mentioned steels, including among others hardening, tempering,carburizing, and nitriding, for the purpose of developing specificuseful properties in articles made from such steels. It should be notedthat the tempering and nitriding operations may, if desired, be carriedout simultaneously.

If desired, steels of the above compositions may be deposited as weldmetal for the purpose of producing localized cutting or wear-resistingportions of an article of manufacture.

Steels of some of the above compositions, due to their great strengthand toughness. are suitable for use as supporting and auxiliary wearingparts in composite tools, employing primary cutting edges or wearingsurfaces formed on elements of hard non-ferrous metallic compositions.

Exceptional hardness is obtainable by appropriate heat treatment ofcertain of the abovementioned compositions. This makes possible toolsparticularly suitable for machining materials of greater hardness thanthose at present I low degree of toughness. Such steels may be utilizedin composite tools by supporting them with stronger or tougher steels ofthe same or other compositions.

Certain compositions made in accordance with this invention have a grainstructure, as cast, so fine as to make practical the production of sometypes of tools, cast to substantially their finished shape, which do notrequire hot work for grain refinement to fit them for use.

The resistance of certain compositions made in accordance with thisinvention to grain growth at temperatures approaching the melting point,makes possible the production therefrom of certain articles ofmanufacture by various processes requiring a high degree of plasticflow, such as die forging, pressing and extruding.

As is well known to those familiar with the art, any specification for aparticular alloying composition must permit of certain variations due tothe fact that in making up the steel it is extremely difficult, if notimpossible, to commercially produce a composition exactly like a givenspecification. It is to be understood, therefore, that throughout thedescription and claims where I have used figures to denote definiteamounts and ranges, such amounts and ranges are to be construed toinclude the range of variations usually permissible in making up steelto given specifications.

It is understood that in the compositions specified therein, minoramounts of other alloying elements and impurities such as manganese,nickel, titanium, tantalum, uranium, copper, aluminum, sulphur,phosphorus, arsenic, tin etc., may be included and when the phrase thebalance being substantially all iron is used, it is intended to includeminor amounts of such elements.

Other forms may be employed embodying the features of my inventioninstead of the one here explained, change being made in the compositionprovided the elements stated in the amounts by any of the followingclaims or the equivalent of such stated elements be employed.

I therefore, particularly point out and distinctly claim as myinvention:-

1. A ferrous alloy comprising: carbon from about 0.15% to about 1.60%;chromium from about 3.25% to about 6.00%; tungsten from about 8.00% toabout 20.00% molybdenum from twelve and one-half per cent totwenty-eight per cent of the amount of tungsten present; silicon from asubstantial amount to about 3.00% vanadium from a substantial amount toabout 6.00%; and the remainder being substantially all iron.

2. A ferrous alloy comprising: carbon from about 0.15% to about 1.60%;chromium from about 3.25% to about 6.00%; tungsten from about 10.32% toabout 19.00%; molybdenum from twelve and one-half per cent totwenty-eight per cent of the amount of tungsten present; silicon from asubstantialamount to about 3.00%; vanadium from a substantial amount toabout 6.00%; and the remainder being substantially all iron.

3. A ferrous alloy comprising: carbon from about 0.15% to about 1.60%;chromium from about 3.25% to about 6.00%; tungsten from about 11.04% toabout 16.50% molybdenum from twelve and one-half per cent totwenty-eight per cent of the amount of tungsten present; silicon from asubstantial amount to about 3.00%; vanadium from a substantial amount toabout 6.00%; and the remainder being substantially all iron.

4. A ferrous alloy comprising: carbon from about 0.15% to about 1.60%;chromium from about 3.25% to about 6.00%; tungsten from about 8.00% toabout 20.00%; molybdenum from twelve and one-half per cent to fifteenper cent of the amount of tungsten present; silicon from a substantialamount to about 3.00%; vanadium from a substantial amount to about6.00%; and the remainder being substantially all iron.

5. A ferrous alloy comprising: carbon from about 0.65% to about 0.90%;chromium'from about 3.37% to about 4.98%; tungsten from about 10.32% toabout 19.00%; molybdenum from twelve and one-half per cent to fifteenper cent of the amount of tungsten present; silicon from about 0.20% toabout 2.20% vanadium' from about 0.45% to about 3.09%; and the remainderbeing substantially all iron.

6. A ferrous alloy comprising: carbon from about 0.65% to about 0.85%;chromium from about 3.42% to about 4.73%; tungsten from about 11.04% toabout 16.50%; molybdenum from twelve and one-half per cent to fifteenper cent of the amount of tungsten present; silicon from about 0.27% toabout 1.00%; vanadium from about 0.68% to about 2.46%; and the remainderbeing substantially all iron.

7. A ferrous alloy comprising: carbon from about 0.15% to about 1.60%;chromium from about 3.25% to about 6.00%; tungsten from about 8.00% toabout 20.00%; molybdenum from fifteen per cent to twenty per cent of theamount of tungsten present; silicon from a. substantial amount to about3.00% vanadium from a substantial amount to about 6.00%; and theremainder being substantially all iron.

8. A ferrous alloy comprising: carbon from about 0.65% to about 0.90%;chromium from about 3.37% to about 4.98%; tungsten from about 10.32% toabout 19.00%; molybdenum from fifteen per cent to twenty per cent of theamount of tungsten present; silicon from about 0.20% to about 2.20%;vanadium from about 0.45% to about 3.09%; and the remainder beingsubstantially all iron.

9. A ferrous alloy comprising: carbon from about 0.65% to about 0.85%;chromium from about 3.42% to about 4.73%; tungsten from about 11.04% toabout 16.50%; molybdenum from fifteen per cent to twenty per cent of theamount of tungsten present; silicon from about 0.27% to about 1.00%;vanadium from about 0.68% to about 2.46%; and the remainder beingsubstantially all iron.

10. A ferrous alloy comprising: carbon from about 0.15% to about 1.60%;chromium from about 3.25% to about 6.00%; tungsten from about 8.00% toabout 20.00%; molybdenum from twenty per cent to twenty-eight per centof the amount of tungsten present; silicon from a substantial amount toabout 3.00%; vanadium from a substantial amount to about 6.00%; and theremainder being substantially all iron.

11. A ferrous alloy comprising: carbon from about 0.65% to about 0.90%;chromium from about 3.37% to about 4.98%; tungsten from about 10.32% toabout 19.00%; molybdenum from twenty per cent to twenty-eight per centof the amount of tungsten present; silicon from about 0.20% to about2.20%; vanadium'from about 0.45% to about 3.09%; and the remainder beingsubstantially all iron.

12. A ferrous alloy comprising: carbon from about 0.65% to about 0.85%;chromium from about 3.42% to about 4.73%; tungsten from about 11.04% toabout 16.50%; molybdenum from twenty per cent to twenty-eight per centof the amount of tungsten present; silicon from about 0.27% to about1.00%; vanadium from about 0.68% to about 2.46%; and the remainder beingsubstantially all iron.

13. A tool formed of a ferrous alloy comprising: carbon from about 0.15%to about 1.60%; chromium from about 3.25% to about 6.00%; tungsten fromabout 8.00% to about 20.00%;

molybdenum from twelve and. one-half per cent to twenty-eight per centof the amount of tungsten present; silicon from a substantial amount toabout 3.00%; vanadium from a substantial amount to about 6.00%; and theremainder being substantially all iron.

JOSEPH V. EMMONS.

